1. Technical Field
The present invention relates generally to shock absorbers for dissipating the kinetic energy of a falling object. More specifically, the invention relates to devices, designed for a single use, that slow and stop the fall of rapidly descending objects, such as free falling humans, fastened to a structure as by a rope or other tether. An energy absorber of this type may work, for example, by elongation, entailing the tearing or drawing out of some of its elements, thus limiting decelerating forces applied to the falling body.
2. Background Information
Many safety devices have been developed for braking the fall of objects from great heights. The present invention is most closely related to the type of shock absorber disclosed in U.S. Pat. No. 4,538,702, issued to Wolner on Sep. 3, 1985. Shock absorbers of this type are of relatively simple construction, relying on the tearing action of a fabric to overcome the momentum of the falling object and bring it to a safe stop, avoiding the likelihood of damage or injury arising from a sudden, jolting halt as when a falling object reaches the full extension of a rope or other tether. In other words, shock absorbers such as these cause controlled, rather than instantaneous, deceleration of a falling body to a stationary position.
The Wolner patent discloses the use of a piece of webbing that has been folded over onto itself several times, with a coil shaped pin inserted through the webbing. A light cover is then placed around the assembly. As the object to which an end of the fall protection device is attached falls, the pin tears the webbing, and the resistance from the webbing as it is being torn absorbs the energy of the falling body steadily decelerating it until it stops. In order for this device to function properly, the pin must be properly positioned and must not become dislodged or otherwise malfunction, since such a malfunction could result in serious injury or death to a human user.
Similarly, U.S. Pat. No. 4,446,944, issued to Forrest et al. on May 8, 1984, discloses a shock absorber having a plurality of energy absorbing straps of graduating lengths. It is intended that each of the shorter straps will break, the shortest being the first to break, the next longest being the second to break, and so on, each strap absorbing some of the kinetic energy of the falling body, until the falling body is brought to rest. In use, such a device has the potential of being damaging to a human user because of the sudden, jarring motions the falling body is subjected to as each of the straps is extended and then broken. Further, the Forrest et al. device must be carefully assembled since a plurality of straps are involved and the stitching or other means of fastening must be carefully placed to ensure proper functioning of the shock absorber.
The shock absorber safety system of the present invention overcomes the difficulties described above and affords other features and advantages heretofore not available.